The present discussion relates to industrial process control monitoring devices. More particularly, the present discussion relates to field devices configured to communicate wirelessly with remote devices in process control systems that are adapted for use in harsh environmental conditions.
Electronic field devices (such as process transmitters) can be used to monitor the operation of industrial processes such as those in oil refineries, chemical processing plants, paper processing plants, biotechnology plants, pharmaceutical plants, food and beverage plants, and the like. Process transmitters for monitoring an industrial process may be used to measure one or more phenomena that are related to or capable of impacting the process. Some phenomena that may be measured in industrial processes include pressure, flow rate, fluid or material level in a tank, temperature, and vibration. Additionally, such field devices may include electronics capable of performing analysis of measured data related to one or more phenomena, diagnostic electronics, or other process monitoring electronic devices, or even electronic, hydraulic, or pneumatic actuator devices used for industrial process control.
Field devices can also include circuitry for communicating over a process control loop with other monitoring or control devices such as, for example, other installed field devices, hand held tools, or equipment that may be remotely located, for example, in a process control room. Data transmitted over the process control loop can be transmitted in either an analog or a digital format. Analog field devices are often connected to other devices via two-wire process control current loops. For example, a number of field devices can be connected to a process control room via a single two-wire control loop.
In addition or alternatively, field devices can have wireless communication technologies incorporated to facilitate communication with other remotely located monitoring and control devices. Wireless communication technologies provide the advantage of simplifying field device implementation because field devices that do not rely on wired communication need not have any wires provided to them. For certain types of wireless communication, an antenna is attached to the field device and is in electrical communication with wireless communication circuitry located with the field device to boost the transmitted signals.
Field devices, including process transmitters, can be routinely located in relatively harsh environments. Such environments may be potentially deleterious to, for example, electrical components and/or electrical connectors of the field device, including connections for two wire communication loops and/or antennas. For example, process transmitters can potentially be installed in locations where they are exposed to liquids, dust and humidity and various industrial contaminants. Some of these field devices may be exposed to potentially corrosive process liquids, such as acid or base solutions, that are a part of the particular industrial process. Such liquids may drip, splash, or be sprayed onto the field. In addition, field devices may be exposed to other materials, such as cleaning agents. In addition, field devices may be exposed to electromagnetic waves that can potentially interfere with the operation of electrical components within the field device, including the process transmitter and wireless communication devices. Furthermore, field devices can be located in external environments, where they can be exposed to, for example, temperature extremes, vibration, precipitation, ultra-violet light, and wind.
In view of the harsh environments in which field devices are installed and in view of the need to provide a wireless signal to remote devices in such environments, there is an ongoing need in the art for industrial process transmitter housing configurations. Such housing configurations require improved robustness with respect to harsh environmental conditions, including exposure to dust, liquids, humidity, and electromagnetic energy. In addition, such devices require an ability to communicate properly with other wireless devices.